CN113767520A

CN113767520A - Battery pack having movable bus bar assembly and secondary battery including the same

Info

Publication number: CN113767520A
Application number: CN202080030070.5A
Authority: CN
Inventors: 金容一; 李康源
Original assignee: LG Energy Solution Ltd
Current assignee: LG Energy Solution Ltd
Priority date: 2019-08-02
Filing date: 2020-07-30
Publication date: 2021-12-07
Anticipated expiration: 2040-07-30
Also published as: CN113767520B; EP3907818A1; JP2022512496A; WO2021025374A1; JP7258278B2; US20220123438A1; EP3907818A4; KR20210015547A

Abstract

Disclosed are a battery pack having a movable bus bar assembly and a secondary battery including the same, and more particularly, a battery pack having a movable bus bar assembly configured such that at least one of a first bus bar frame located at a front surface of a pack case, a second bus bar frame located at a rear surface of the pack case, a first bus bar connected to the first bus bar frame, and a second bus bar connected to the second bus bar frame is movable in a direction toward a side plate of the pack case, whereby a short circuit between leads may be minimized, and a secondary battery including the same.

Description

Battery pack having movable bus bar assembly and secondary battery including the same

Technical Field

This application claims the benefit of priority from korean patent application No. 2019-0094564, filed on 8/2/2019, the entire disclosure of which is incorporated herein by reference.

The present invention relates to a battery pack having a movable bus bar assembly and a secondary battery including the same, and more particularly, to a battery pack having a movable bus bar assembly configured such that at least one of a first bus bar frame located at a front surface of a pack case, a second bus bar frame located at a rear surface of the pack case, a first bus bar connected to the first bus bar frame, and a second bus bar connected to the second bus bar frame is movable in a direction toward a side plate of the pack case, whereby a short circuit between leads may be minimized, and a secondary battery including the same.

Background

As the technology of mobile devices such as mobile phones, laptop computers, camcorders, and digital cameras has been developed and the demand for them has increased, research into secondary batteries capable of being charged and discharged has been actively conducted. In addition, secondary batteries, which are energy sources replacing fossil fuels causing air pollution, have been applied to Electric Vehicles (EV), Hybrid Electric Vehicles (HEV), and plug-in hybrid electric vehicles (P-HEV), and thus there is an increasing need for development of secondary batteries.

As secondary batteries currently commercialized, there are nickel cadmium batteries, nickel hydrogen batteries, nickel zinc batteries, and lithium secondary batteries. Among them, lithium secondary batteries are receiving attention because they have almost no memory effect as compared to nickel-based secondary batteries, and thus can be freely charged and discharged, have a very low self-discharge rate, and have a high energy density.

In such a lithium secondary battery, a lithium-based oxide and a carbon material are used as a positive electrode active material and a negative electrode active material, respectively. The lithium secondary battery includes: an electrode assembly configured such that a positive electrode plate covered with a positive electrode active material and a negative electrode plate covered with a negative electrode active material are disposed with a separator interposed therebetween; and a case member, i.e., a battery case, configured to accommodate the electrode assembly together with the electrolyte in a sealed state.

Based on the shape of the battery case, the secondary battery is classified into: a cylindrical battery having an electrode assembly mounted in a cylindrical metal can, a prismatic battery having an electrode assembly mounted in a prismatic metal can, and a pouch-shaped battery having an electrode assembly mounted in a pouch-shaped case made of an aluminum laminate sheet.

A secondary battery for a small-sized device includes several battery cells. However, for a vehicle, the battery module includes a plurality of battery cells electrically connected to each other. In order to increase the capacity and output of the battery module, a plurality of battery cells are connected in series and parallel with each other. In this case, a plurality of battery cells, i.e., secondary batteries, are stacked, and the battery module generally includes a bus bar module (buss bar module) configured to electrically connect the battery cells to each other. The bus bar module includes bus bars configured to connect electrode leads connected to the respective battery cells to each other. The bus bar module may be formed at one side surface of the battery module.

Fig. 1 is a perspective view of a conventional battery pack. As shown in fig. 1, the conventional battery pack includes: a sub-module having at least two unit cells 10 arranged side by side, each unit cell 10 including an electrode assembly 11 and a positive electrode lead 12 and a negative electrode lead protruding from opposite sides of the electrode assembly 11; a bus bar assembly 20, the bus bar assembly 20 including a bus bar 22 electrically connected to a lead of the sub-module and a bus bar frame 21 configured to support the bus bar 22; and a battery pack case 30, the battery pack case 30 being configured to support the bus bar assembly 20 while accommodating the sub-modules.

That is, in order to satisfy the high capacity of the electric vehicle or the hybrid electric vehicle, as shown in fig. 1, a plurality of batteries are connected to each other. At this time, the lead is fixed to the bus bar 22 by welding, and the bus bar 22 is fixed to the pack case 30 via the bus bar frame 21.

In addition, a battery swelling phenomenon in which the unit cells swell may occur due to various reasons such as repeated charge and discharge, overcharge, and external impact. Therefore, the adjacent unit cells are pushed toward the

side plates

31 and 32 of the pack case. As a result, the battery pack may catch fire or explode due to the internal short circuit. In addition, the battery pack may expand beyond an allowable space in which the battery pack is mounted, thereby deteriorating safety of structures around the battery pack.

More specifically, the battery stack includes a minimum of several unit cells or a maximum of several tens of unit cells stacked side by side. In the case where the unit cells are expanded due to swelling, the unit cells located at the edges of the cell stack are greatly pushed outward from their original positions. However, since the bus bar and the bus bar frame are fixed at their original positions, high tension is generated at the lead wires connecting the unit cells and the bus bar to each other, so that the lead wires may be disconnected. As a result, the performance of the unit cells and the battery pack is deteriorated.

In order to solve the above-described problem, patent document 1 discloses a bus bar module configured such that a connector of an inverted U shape, which is bendable or deformable, is provided between support frames of support members integrally formed with a plurality of bus bars by insert molding.

Patent document 2 discloses a bus bar and a battery module, the bus bar including: a first terminal connection part formed of a conductive conical elastic member configured to contact a terminal of a battery cell; and a second terminal connection part formed of a conductive conical elastic member configured to contact a terminal of another battery cell, the first and second terminal connection parts being spaced apart from each other by a distance between the terminals.

Patent document 3 discloses a battery system configured to interrupt power supply to a battery cell module when a swelling phenomenon occurs due to overcharge.

However, patent document 1 and patent document 2 have problems in that: it is difficult to secure a sufficient moving distance due to the swelling of the battery, and patent document 3 has a problem in that: even if the battery life is maintained, the battery cannot be used.

Prior art document-

-patent document

Japanese patent application laid-open No. 2015-159024 ("patent document 1")

Japanese patent application laid-open No. 2016-

Korean patent application laid-open No. 2014-charge 0012264 ("patent document 3")

Disclosure of Invention

Technical problem

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a battery pack capable of reducing loads applied to tabs and lead wires of unit cells and connection between the lead wires and bus bars even when a swelling phenomenon occurs, thereby preventing damage to the tabs and lead wires of the unit cells and connection between the lead wires and the bus bars, and a secondary battery including the same.

It is another object of the present invention to provide a battery pack capable of preventing a reduction in battery performance due to a failure of some unit cells caused when swelling occurs due to battery use such as repeated charging and discharging of a battery and natural phenomena, and preventing combustion and explosion of the battery, and a secondary battery including the same.

Technical scheme

In order to achieve the above object, a battery pack according to the present invention includes: sub-modules (100), each sub-module (100) having one or more unit cells (110) disposed therein, each unit cell (110) including an electrode assembly (111), and a positive electrode lead (112) and a negative electrode lead (113) disposed on opposite sides of the electrode assembly (111); a bus bar assembly (200), the bus bar assembly (200) being configured to connect the sub-modules (100) to each other in series or in parallel, the bus bar assembly (200) including a first bus bar frame (210), a second bus bar frame (220), a first bus bar (230) connected to the first bus bar frame (210), and a second bus bar (240) connected to the second bus bar frame (220); and a pack case (400), the pack case (400) being configured to support the bus bar assembly (200) while accommodating the sub-module (100), the pack case (400) including: a first side plate (410) arranged side by side at one side of the sub-module (100), a second side plate (420) arranged side by side at the other side of the sub-module (100), and a bottom plate (430) at the bottom of the sub-module (100), wherein at least one of the first bus bar frame (210), the second bus bar frame (220), the first bus bar (230) and the second bus bar (240) is movable in a direction towards the first side plate (410) and/or the second side plate (420).

In addition, in the battery pack according to the present invention, the sub-module (100) may be N sub-modules, N being a natural number equal to or greater than 3, each of the N sub-modules has two or more unit cells (110) arranged in parallel, and in order to connect the N sub-modules (100) to each other in series, the first bus bar frame (210), the first bus bar (230), and a connection bus bar (250) configured to connect every two adjacent sub-modules (100) after the N-2 th sub-module (100) to each other in series may be located at a front surface of the pack case (400), and the second bus bar frame (220) and the second bus bar (240) configured to connect every two adjacent sub-modules (100) from the N-2 th sub-module (100) in series with each other may be located at a rear surface of the pack case (400).

Further, in the battery pack according to the present invention, the sub-module (100) may be N sub-modules, N being a natural number equal to or greater than 2, each of the N sub-modules having two unit cells (110) positioned such that positive and negative terminals face each other, and in order to connect the unit cells (110) in series with each other, the positive and negative leads (112, 113) disposed at one side may be respectively fixed to a plurality of first bus bars (230) spaced apart from each other by a predetermined distance, and the negative and positive leads (113, 112) disposed at the other side may be fixed to the same second bus bar (240).

Further, in the battery pack according to the present invention, the sub-module (100) may be N sub-modules, N being a natural number equal to or greater than 2, each of the N sub-modules having one unit cell (110), and in order to connect the unit cells (110) in series to each other, the positive lead (112) and the negative lead (113) disposed adjacent to each other at one side may be fixed to the first bus bar (230), and the negative lead (113) and the positive lead (112) disposed adjacent to each other at the other side may be fixed to the second bus bar (240).

Further, in the battery pack according to the present invention, only the first bus bar frame (210) and/or the second bus bar frame (220) may be movable in a state in which the first bus bar (230) and the second bus bar (240) are fixed to the first bus bar frame (210) and the second bus bar frame (220), respectively.

Further, in the battery pack according to the present invention, a fixing shaft may be disposed between the first side plate (410) and the second side plate (420), and the first bus bar frame (210) and/or the second bus bar frame (220) may be provided with a first engaging protrusion connected with the fixing shaft.

Further, in the battery pack according to the present invention, the base plate (430) may be provided with a rail (431), and the first bus bar frame (210) and/or the second bus bar frame (220) may be provided with a second catching protrusion connected with the rail (431).

Further, in the battery pack according to the present invention, each of the first bus bar frame (210), the second bus bar frame (220), the first bus bar (230), and the second bus bar (240) is independently movable in a direction toward the first side plate (410) and/or the second side plate (420).

Furthermore, in the battery pack according to the present invention, the first bus bar (230) and/or the second bus bar (240) are movable.

Further, in the battery pack according to the present invention, the first bus bar frame (210) may be provided with a first guide bar (213), and the first bus bar frame (230) may be provided with a first hole (232) configured to receive the first guide bar (213), the first hole (232) being a long hole.

Further, in the battery pack according to the present invention, the first bus bar frame (210) may be further provided with a first fastening member (233) mounted to the first guide bar (213).

Further, in the battery pack according to the present invention, the second bus bar frame (220) may be provided with a second guide bar (223), and the second bus bar frame (240) may be provided with a second hole (242) configured to receive the second guide bar (223), the second hole (242) being a long hole.

Further, in the battery pack according to the present invention, the second bus bar frame (220) may be further provided with a second fastening member (242) mounted to the second guide bar (223).

Further, in the battery pack according to the present invention, the connection bus bar (250) may be made of a conductive material and have a corrugated structure.

Further, in the battery pack according to the present invention, the connection bus bar (250) may be made of an elastic conductive material.

Further, in the battery pack according to the present invention, the connection bus bar (250) may have a coil shape.

Further, in the battery pack according to the present invention, each of the first bus bar (230) and the second bus bar (240) may have the same number of slits as the unit cells (110), and the electrode of each of the unit cells (110) may extend through the respective slits and then be fixed to different positions.

Further, in the battery pack according to the present invention, each of the first bus bar (230) and the second bus bar (240) may have a smaller number of slits than the number of the unit cells (110), and two or more electrodes may be sequentially stacked and fixed at the same point of the bus bars.

Further, in the battery pack according to the present invention, a buffer member (300) may be further provided between the sub-modules (100).

Further, a secondary battery according to the present invention includes the above battery pack.

Drawings

Fig. 1 is a perspective view of a conventional battery pack.

Fig. 2 is a perspective view of a battery pack according to a first preferred embodiment of the present invention when viewed from one side thereof.

Fig. 3 is a perspective view of a battery pack according to a first preferred embodiment of the present invention, when viewed from the other side thereof.

Fig. 4 is a plan sectional view of the battery pack shown in fig. 2.

Fig. 5 is an enlarged view of a dotted line portion of fig. 2, which is a perspective view illustrating a coupling structure between a bus bar frame and a bus bar.

Fig. 6 is a perspective view illustrating a modified coupling structure between the bus bar frame of fig. 5 and the bus bar.

Fig. 7 is a view illustrating a first modification of the connecting bus bar of fig. 5.

Fig. 8 is a view illustrating a second modification of the connecting bus bar of fig. 5.

Fig. 9 is a perspective view of a battery pack according to a second preferred embodiment of the present invention when viewed from one side thereof.

Fig. 10 is a perspective view of a battery pack according to a second preferred embodiment of the present invention, when viewed from the other side thereof.

Fig. 11 is an enlarged view of a portion a of fig. 9.

Fig. 12 is an enlarged view of a portion B of fig. 9.

Fig. 13 is a sectional view illustrating a coupling structure between bus bars and electrode leads in a battery pack according to a third preferred embodiment of the present invention.

Fig. 14 is a sectional view illustrating a coupling structure between bus bars and electrode leads in a battery pack according to a fourth preferred embodiment of the present invention.

Fig. 15 is a sectional view illustrating a coupling structure between bus bars and electrode leads in a battery pack according to a fifth preferred embodiment of the present invention.

Detailed Description

In this application, it should be understood that the terms "comprises," "comprising," "includes," "including," and the like, specify the presence of stated features, integers, steps, operations, elements, components, or groups thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or groups thereof.

Further, the same reference numerals will be used throughout the drawings to designate portions that perform similar functions or operations. In the case where one portion is referred to as being connected to another portion in the present application, it may be not only that one portion is directly connected to the other portion but also that one portion is indirectly connected to the other portion via another portion. In addition, the inclusion of a certain element does not mean that other elements are excluded, but means that other elements may be further included unless otherwise specified.

Hereinafter, a battery pack having a movable bus bar assembly and a secondary battery including the same according to the present invention will be described with reference to the accompanying drawings.

Fig. 2 is a perspective view of a battery pack according to a first preferred embodiment of the present invention when viewed from one side thereof, fig. 3 is a perspective view of the battery pack according to the first preferred embodiment of the present invention when viewed from the other side thereof, and fig. 4 is a plan sectional view of the battery pack shown in fig. 2.

Referring to fig. 2 to 4, the battery pack according to the first embodiment of the present invention includes a sub-module 100, a bus bar assembly 200, a buffer member 300, and a pack case 400.

The sub-module 100 is first described. The sub-module 100 includes at least three unit cells 110, each unit cell 110 including an electrode assembly 111, and a positive electrode lead 112 and a negative electrode lead 113 disposed at opposite sides of the electrode assembly 111, wherein the unit cells 110 are arranged in parallel.

In addition, the electrode assembly 111 may be: a jelly-roll type electrode assembly configured to have a structure in which a long sheet type positive electrode and a long sheet type negative electrode are wound with a separator provided therebetween; a stacking type electrode assembly including unit cells each configured to have a structure in which a rectangular positive electrode and a rectangular negative electrode are stacked with a separator interposed therebetween; a stacking-folding type electrode assembly configured to have a structure in which unit cells are wound using a long separation film; or a laminate stacking type electrode assembly configured to have a structure in which unit cells are stacked with a separator interposed therebetween and then attached to each other. However, the present invention is not limited thereto.

The electrode assembly is mounted in a case, which is generally configured to have a laminate structure including an inner layer, a metal layer, and an outer layer. The inner layer is in direct contact with the electrode assembly, and thus the inner layer must exhibit high insulation and high electrolyte resistance. Further, the inner layers must have high sealability in order to hermetically seal the housing from the outside, i.e., the thermal bonding seal portion between the inner layers must exhibit excellent thermal bonding strength. The inner layer may be made of a resin selected from the group consisting of polyolefin-based resins such as polypropylene, polyethylene-acrylic acid or polybutylene, which exhibit excellent chemical resistance and high sealability; polyurethane resin and polyimide resin. However, the present invention is not limited thereto. Most preferably, polypropylene exhibiting excellent mechanical physical properties such as tensile strength, rigidity, surface hardness and impact strength, as well as excellent chemical resistance is used.

The metal layer adjacent to the inner layer corresponds to a barrier layer configured to prevent moisture or various gases from penetrating into the battery from the outside. Aluminum foil, which is light and easy to form, may be used as a preferred material for the metal layer.

The outer layer is disposed on the other surface of the metal layer. The outer layer may be made of a heat-resistant polymer exhibiting excellent tensile strength, moisture permeation resistance, and air permeation resistance, such that the outer layer exhibits high heat resistance and chemical resistance while protecting the electrode assembly. As an example, the outer layer may be made of nylon or polyethylene terephthalate. However, the present invention is not limited thereto.

In addition, the leads, i.e., the cathode lead 112 and the anode lead 113, may be exposed outside the case after being electrically connected to the cathode tab and the anode tab of the electrode assembly, respectively. Alternatively, the lead may directly connect the electrode assembly and the exterior of the case to each other without the cathode tab and the anode tab. However, the present invention is not limited thereto. The above-described unit cells correspond to a generally known structure, and thus a more detailed description thereof will be omitted.

The sub-module 100 refers to a structure configured such that a plurality of unit cells 110 are stacked side by side in a horizontal direction or a vertical direction in order to meet the required capacity or output of a battery pack, each unit cell 110 including an electrode assembly 111 and electrode leads 112 and 113 extending from the electrode assembly 111. Fig. 2 and 3 show that one sub-module 100 includes three unit cells 110. However, this is merely exemplary. It is apparent that the sub-module 100 may include more than two unit cells 110.

A plurality of sub-modules 100 each configured as described above are accommodated in the battery pack case 400 in a state of being arranged side by side.

The bus bar assembly 200 is configured to fix the unit cells 110 constituting each sub-module 100 to the pack case 400 while connecting the unit cells 110 in series or in parallel with each other. The bus bar assembly 200 includes at least one bus bar frame, at least one bus bar, and/or a connecting bus bar.

Specifically, referring to fig. 2, a plurality of first bus bars 230 configured to connect three unit cells 110 in parallel with each other and a first bus bar frame 210 configured to support and fix the first bus bars 230 are located at the front surface of the battery pack.

That is, the positive electrode lead 112 or the negative electrode lead 113 extending from the electrode assembly 111 of each unit cell 110 extends through the first slit 231 of the corresponding one of the primary bus bars 230 and is then bent. Subsequently, the positive electrode lead 112 or the negative electrode lead 113 is fixed to the outer surface of the first bus bar 230 using a known fixing method such as laser welding or resistance welding.

Further, in order to connect the sub-modules 100 in series with each other, a connection bus bar 250 bent in a predetermined shape is provided between the adjacent sub-modules 100. In the same manner as in the case of the positive electrode lead 112 and the first bus bar 230, the connecting bus bar 250 interconnects the first bus bars 230 using a known fixing means.

In addition, no connecting bus bar 250 is provided between the first and second primary bus bars located at the leftmost side of the battery pack 1 (at the uppermost portion of the battery pack 1 in fig. 2). This structure is provided in order to connect the sub-modules 100 in series with each other. These sub-modules are electrically connected to each other via the second bus bar 240 of the rear surface of the battery pack.

The rear surface of the battery pack will be described in detail with reference to fig. 3. A plurality of second bus bars 240 configured to connect the unit cells 110 constituting each sub-module 100 in series with each other and a second bus bar frame 220 configured to support and fix the second bus bars 240 are located at the rear surface of the battery pack according to the present invention.

Therefore, the unit cells 110 in the single sub-module 100 are connected in parallel with each other, and the sub-modules 100 are connected in series with each other via the first bus bar 210 or the second bus bar 220 (see fig. 4).

An elastic buffer member 300 may be disposed between the sub-module 100 and another sub-module 100 adjacent thereto. The buffer member 300 is configured to minimize an external force transmitted to the sub-module 100 disposed adjacent to a specific unit cell 110 when the specific unit cell 110 swells, thereby preventing a short circuit between the lead wires.

The pack case 400 serves to support the bus bar assembly 200 while accommodating the sub-modules 100. The battery pack case 400 includes: a first side plate 410 arranged side by side on one side of the sub-module 100; a second side plate 420 disposed side by side at the other side of the sub-module 100; and a bottom plate 430 at the bottom of the sub-module 100.

The first side plate 410, the second side plate 420, and the bottom plate 430 may be assembled using a known fixing method such as an interference fit method, a bolt fastening method, or a welding method. An adhesive sealant may be interposed between the respective assembly portions.

In addition, in order to maintain the distance between the first and

second side plates

410 and 420 even if the unit cells 110 are expanded due to swelling, a pair of first and

second fixing shafts

440 and 450 may be further provided at the front and rear surfaces of the battery pack, respectively.

The battery pack according to the present invention may be configured to have a structure in which at least one of the first bus bar frame 210, the second bus bar frame 220, the first bus bar 230, and the second bus bar 240 is movable toward the first side plate 410 and/or the second side plate 420.

First, a structure in which the first bus bar 230 and the second bus bar 240 are movable in a state in which the first bus bar frame 210 and the second bus bar frame 220 are fixed to the pack case 400 will be described with reference to fig. 5 to 8.

The first bus bar 230 having the plurality of first slits 231 is provided with at least one first hole 232 formed at each of upper and lower portions of the first bus bar 230, the first hole 232 being a long hole. The first guide rod 213 protruding from the first bus bar frame 210 is inserted into the first hole 232. Here, the height of the first guide rod 213 is preferably slightly greater than the outer diameter of the first hole 232 so that the first guide rod 213 can move left and right along the first hole 232. More specifically, the height of the first guide rod 213 may be 1 to 10mm greater than the outer diameter of the first hole 232.

In fig. 5, the first hole is shown as a long oval hole. However, it is apparent that the first hole may be configured as a long hole structure having any of various shapes such as a rectangle.

In addition, it is preferable that an internal thread is formed at an inner surface of the first guide rod 213 so that the first bus bar 230 is detachably attached to the first bus bar frame 210. It is also preferable that a first fastening member 233 is provided, the first fastening member 233 having an external thread formed on an outer surface of a cylindrical body thereof so as to be fastened to the internal thread by engagement of the external and internal threads. More preferably, a head portion is provided at one side of the cylindrical body such that the first fastening member has a "T" shape or a "l" shape.

In the above structure, when the electrode assembly 111 is expanded, the entire first bus bar frame 210 may move left and right along the first hole 232 by a predetermined distance. As a result, short circuits between the leads can be prevented. In addition, the attachment and detachment between the first bus bar frame 210 and the first bus bar 230 is very easily accomplished.

Fig. 6 is a perspective view illustrating a modified coupling structure between the bus bar frame of fig. 5 and the bus bar. The coupling structure shown in this figure is identical in construction to the coupling structure shown in fig. 5 except for the first guide rod 213 and the first fastening member 233, and thus only the differences will be described hereinafter.

The first guide bar 213 and the first fastening member 233 may be coupled to each other by interference fit. Specifically, the first guide rod 213 may have a hollow quadrangular prism shape, and the first fastening member 233 may include a head portion and an insertion portion configured to be inserted into the first guide rod 213 in a quadrangular prism shape.

Of course, it is apparent that the cross section of the insertion portion of the first fastening member 233 must be slightly larger than the inner cross section of the first guide rod 213 so that the first fastening member 233 is not too loose. In the figures, each of the first guide bar and the first fastening member is shown as being rectangular. However, it is apparent that each of the first guide bar and the first fastening member may have any of various shapes such as a triangle or a pentagon.

In addition, although the first fastening member 233 is inserted into the first guide bar 213, in order to achieve easy assembly between the first guide bar 213 and the first fastening member 233 and prevent interference with the movement of the first bus bar 230, it is preferable that the first guide bar 213 is inserted into the first fastening member 233.

Fig. 7 is a diagram illustrating a first modification of the connecting bus bar of fig. 5. The coupling structure shown in this figure is identical in construction to the coupling structure shown in fig. 5 except for the connection bus bar 250, and thus only the connection bus bar 250 will be described hereinafter.

The connection bus bar 250 according to the first modification may be made of a conductive material and may have a corrugated structure. Although the primary bus bar 230 is movable along the first guide bar 213, it is difficult to secure a sufficient moving distance only by the buffering force of the buffering member 300 and the connecting bus bar 250 bent to have a predetermined shape. However, as in the first modification, in the case of employing the connecting bus bar 250 having the corrugated structure, a longer moving distance can be ensured, thereby preventing short-circuiting between the leads. Here, the conductive material is not particularly limited as long as the conductive material can allow conduction.

Fig. 8 is a diagram illustrating a second modification of the connecting bus bar of fig. 5. The coupling structure shown in this figure is identical in construction to the coupling structure shown in fig. 5 except for the connection bus bar 250, and thus only the connection bus bar 250 will be described hereinafter.

The connecting bus bar 250 according to the second modified example is not particularly limited as long as the connecting bus bar is made of an elastic conductive material. As an example, the connection bus bar may have a corrugated structure or a coil shape. Here, in the case where the connection bus bar is a conductive coil, the connection bus bar may be made of conductive rubber, gold-silver nanocomposite formed by coating the surface of silver nanowires with gold and mixing it with poly (Styrene-Butadiene-Styrene) (SBS), carbon nanotube, or carbon-rubber composite.

Of course, in order to achieve the same purpose and function, the bus bars may be connected to each other somewhat loosely using flexible electric wires, although the length of each flexible electric wire is neither increased nor decreased.

In the case of employing the connecting bus bar 250 according to the second modification, the moving distance can be easily secured and the first bus bar 230 can be moved with a small force.

Although the structure in which the primary bus bar 230 is movable at the front surface of the battery pack is described above with reference to fig. 5 to 8, it is apparent that the same structure may be employed for the secondary bus bar 240 such that the secondary bus bar 240 is movable.

Next, a structure in which the first bus bar frame 210 and the second bus bar frame 220 are movable in a state in which the first bus bar 230 and the second bus bar 240 are fixed to the first bus bar frame 210 and the second bus bar frame 220, respectively, will be described with reference to fig. 9 to 12.

Fig. 9 is a perspective view of a battery pack according to a second preferred embodiment of the present invention when viewed from one side thereof, and fig. 10 is a perspective view of the battery pack according to the second preferred embodiment of the present invention when viewed from the other side thereof.

The battery pack according to the present embodiment is identical in construction to the battery pack according to the first embodiment shown in fig. 2 and 3, except that each bus bar frame is provided with a snap projection and the bottom plate is formed with a rail, and thus only the differences will be described hereinafter.

In the battery pack according to the second preferred embodiment of the present invention, the 1 st 'engagement protrusion 211 is formed at the upper portion of the first bus bar frame 210, and the 2 nd' engagement protrusion 212 is formed at the lower portion of the first bus bar frame 210.

The 1 st' catching protrusion 211 will be described in more detail with reference to fig. 11 (an enlarged view of part a of fig. 9). A 1 st' snap protrusion 211 having a half-ring shape such as a C shape is formed at an upper portion of the first bus bar frame 210. The 1 st' catching protrusion 211 is fixed to the first fixing shaft 440.

Referring to fig. 12 (an enlarged view of a portion B of fig. 9), a lower portion of the first bus bar frame 210 is formed with

A 2 nd 'snap protrusion 212 of a shape, and a rail 431 having a recess formed therein is provided at the bottom plate 430 such that the 2 nd' snap protrusion 212 is fixed to the rail 431.

In short, as shown in fig. 11 and 12, the 1 st 'snap protrusion 211 of the first bus bar frame 210 is fixed to the first fixing shaft 440, and the 2 nd' snap protrusion 212 is fixed to the rail 431 of the bottom plate 430, whereby the first bus bar frame is slidable left and right.

Although detailed drawings and descriptions of the rear surface of the battery pack according to the present invention are omitted, it is apparent that the catching protrusion and the rail having the same structure as those shown in fig. 11 and 12 may be provided.

In addition, each of the 1 st ' and 2 nd '

snap protrusions

211 and 212 of the first bus bar frame 210 may have a half ring shape such as a C shape, and the 1 st ' and 2

nd snap protrusions

211 and 212 may be fixed to the first and second

fixed shafts

440 and 450, respectively.

Further, the first and second bus bars 230 and 240 may not be fixed to the first and second bus bar frames 210 and 220, respectively, but may employ a structure in which the first and second bus bars 230 and 240 are movable as described with reference to fig. 5 to 8.

In this case, each of the first bus bar frame 210, the second bus bar frame 220, the first bus bar 230, and the second bus bar 240 is independently movable, so that short circuits between the electrode leads can be most effectively prevented.

In the third embodiment of the present invention, bus bars having the same shape may be connected to the front and rear surfaces of each sub-module, and lead wires constituting a single sub-module may be fixed to the bus bars in a state of overlapping each other.

Specifically, a buffer member 300 is provided between sub-modules each including three unit cells, and the first and second bus bars 230 and 240 are electrically connected to each other via a connection bus bar 250, each of the first and second bus bars 230 and 240 having the same number of slits as the lead wires. Further, the positive electrode lead 112 or the negative electrode lead 113 extending through the respective slits are fixed to overlap each other at the same position of the respective bus bars positioned in a spaced state from each other.

Of course, although not shown in the drawings, the number of slits in the bus bar may be smaller than the number of leads. In this case, more than one lead may extend through a single slit and then may be fixed to the bus bar at the same position overlapping each other.

In the above structure, the size of each bus bar can be reduced. Further, a space in which the bus bar is movable can be easily secured.

Fig. 13 is a sectional view illustrating a coupling structure between bus bars and electrode leads in a battery pack according to a fourth preferred embodiment of the present invention.

In the fourth embodiment of the present invention, all the unit cells are connected in series with each other. In the single sub-module, the unit cells are positioned such that the positive and negative terminals face each other. Specifically, the positive electrode lead 112 and the negative electrode lead 113, which are disposed at one side to face the same direction, are respectively fixed to the first bus bars 230 spaced apart from each other by a predetermined distance. Further, the first bus bars 230 are electrically connected to each other via the connection bus bar 250. In addition, the negative electrode lead 113 and the positive electrode lead 112 disposed at the other side are fixed to the same second bus bar 240. Cushioning members 300 may be selectively disposed between the sub-modules.

In the same manner as in the fourth embodiment, all the unit cells are connected in series with each other. However, in the fifth embodiment, the cathode lead 112 and the anode lead 113 are fixed to different first bus bars 230 or different second bus bars 240.

Specifically, the cathode lead 112 and the anode lead 113, which are disposed to face the same direction on one side, are respectively fixed to the first bus bars 230 spaced apart from each other by a predetermined distance, and the anode lead 113 and the cathode lead 112, which are disposed on the other side, are also respectively fixed to the second bus bars 240 spaced apart from each other by a predetermined distance. Further, the first bus bar 230 and the second bus bar 240 are connected to each other via a plurality of connection bus bars 250.

In addition, although only sectional views of the bus bars and the electrode leads are shown in the third to fifth embodiments, it is apparent that the bus bar moving structure, the bus bar frame moving structure, and the elastic connection bus bars described in the first and second embodiments may be applied.

Although the present invention has been described in detail, those skilled in the art will appreciate that the detailed description thereof discloses only the preferred embodiments of the invention and thus does not limit the scope of the invention. Accordingly, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope and technical spirit of the present invention, and it will be apparent that such changes and modifications fall within the scope of the appended claims.

Description of reference numerals

1: battery pack

100: submodule

110: unit cell

111: electrode assembly 112: positive electrode lead

113: negative electrode lead

200: bus bar assembly

210: first bus bar frame

211: 1 st' snap projection 212: 2 nd' snap-in projection

213: first guide rod

220: second bus bar frame

221: 1 st' engaging projection

230: first bus bar

231: first slit 232: first hole

233: first fastening member

240: second bus bar

241: second slit

250: connecting bus bar

300: buffer member

400: battery pack case

410: first side plate

420: second side plate

430: base plate

431: track

440: first fixed shaft

450: a second stationary shaft.

Industrial applicability

The battery pack according to the present invention is advantageous in that the bus bars and/or the bus bar frame are movable, thereby preventing damage to the tabs and the lead wires of the unit cells and damage to the connection between the lead wires and the bus bars even when the swelling phenomenon occurs.

Further, in the battery pack according to the present invention, it is possible to prevent the overall performance of the battery pack from being lowered and to improve the safety of the battery by preventing damage to the tabs and the lead wires of the unit cells and damage to the connection between the lead wires and the bus bars.

Further, in the battery pack according to the present invention, the reuse of the battery can be achieved while increasing the life span of the battery, so that the amount of waste can be reduced.

Claims

1. A battery pack, comprising:

sub-modules (100), each sub-module (100) having one or more unit cells (110) disposed therein, each unit cell (110) including an electrode assembly (111), and a positive electrode lead (112) and a negative electrode lead (113) disposed on opposite sides of the electrode assembly (111);

a bus bar assembly (200), the bus bar assembly (200) being configured to connect the sub-modules (100) to each other in series or in parallel, the bus bar assembly (200) including a first bus bar frame (210), a second bus bar frame (220), a first bus bar (230) connected to the first bus bar frame (210), and a second bus bar (240) connected to the second bus bar frame (220); and

a battery pack case (400), the battery pack case (400) being configured to support the bus bar assembly (200) while accommodating the sub-module (100), the battery pack case (400) including: a first side plate (410) arranged side by side on one side of the sub-module, a second side plate (420) arranged side by side on the other side of the sub-module (100), and a bottom plate (430) at the bottom of the sub-module (100), wherein

At least one of the first bus bar frame (210), the second bus bar frame (220), the first bus bar (230), and the second bus bar (240) is movable in a direction toward the first side plate (410) and/or the second side plate (420).

2. The battery pack of claim 1, wherein

The sub-module (100) is N sub-modules, N being a natural number equal to or greater than 3, each of the N sub-modules having two or more unit cells (110) arranged in parallel, and

in order to connect the N sub-modules (100) to each other in series, the first bus bar frame (210), the first bus bar (230), and a connection bus bar (250) configured to connect every two adjacent sub-modules (100) after the N-2 th sub-module (100) to each other in series are located at a front surface of the pack case (400), and the second bus bar frame (220) and the second bus bar (240) configured to connect every two adjacent sub-modules (100) from the N-2 th sub-module (100) to each other in series are located at a rear surface of the pack case (400).

3. The battery pack of claim 1, wherein

The sub-module (100) is N sub-modules, N being a natural number equal to or greater than 2, each of the N sub-modules has two unit cells (110) positioned such that positive and negative terminals face each other, and

in order to connect the unit cells (110) in series with each other, the positive electrode lead (112) and the negative electrode lead (113) disposed at one side are respectively fixed to a plurality of first bus bars (230) spaced apart from each other by a predetermined distance, and the negative electrode lead (113) and the positive electrode lead (112) disposed at the other side are fixed to the same second bus bar (240).

4. The battery pack according to claim 1,

the sub-modules (100) are N sub-modules, N being a natural number equal to or greater than 2, each of the N sub-modules having one unit cell (110), and

in order to connect the unit cells (110) in series with each other, the positive electrode lead (112) and the negative electrode lead (113) disposed adjacent to each other on one side are fixed to the first bus bar (230), and the negative electrode lead (113) and the positive electrode lead (112) disposed adjacent to each other on the other side are fixed to the second bus bar (240).

5. The battery pack according to claim 1, wherein only the first bus bar frame (210) and/or the second bus bar frame (220) is movable in a state in which the first bus bar (230) and the second bus bar (240) are fixed to the first bus bar frame (210) and the second bus bar frame (220), respectively.

6. The battery pack according to claim 5, wherein a fixing shaft is provided between the first side plate (410) and the second side plate (420), and the first bus bar frame (210) and/or the second bus bar frame (220) is provided with a first catching protrusion connected with the fixing shaft.

7. The battery pack according to claim 5, wherein the bottom plate (430) is provided with a rail (431), and the first bus bar frame (210) and/or the second bus bar frame (220) is provided with a second catching protrusion connected with the rail (431).

8. The battery pack according to claim 1, wherein each of the first bus bar frame (210), the second bus bar frame (220), the first bus bar (230), and the second bus bar (240) is independently movable in a direction toward the first side plate (410) and/or the second side plate (420).

9. The battery pack of claim 1, wherein the first bus bar (230) and/or the second bus bar (240) are movable.

10. The battery pack according to claim 9, wherein the first bus bar frame (210) is provided with a first guide rod (213), and the first bus bar frame (230) is provided with a first hole (232) configured to receive the first guide rod (213), the first hole (232) being an elongated hole.

11. The battery pack according to claim 10, wherein the first bus bar frame (210) is further provided with a first fastening member (233) mounted to the first guide bar (213).

12. The battery pack according to claim 10, wherein the second bus bar frame (220) is provided with a second guide rod (223), and the second bus bar frame (240) is provided with a second hole (242) configured to receive the second guide rod (223), the second hole (242) being an elongated hole.

13. The battery pack according to claim 12, wherein the second bus bar frame (220) is further provided with a second fastening member (242) mounted to the second guide bar (223).

14. The battery pack according to claim 1, wherein the connection bus bar (250) is made of a conductive material and has a corrugated structure.

15. The battery pack according to claim 1, wherein the connection bus bar (250) is made of an elastic conductive material.

16. The battery pack according to claim 15, wherein the connection bus bar (250) has a coil shape.

17. The battery pack according to claim 1, wherein each of the first bus bar (230) and the second bus bar (240) has the same number of slits as the unit cells (110), and the electrode of each of the unit cells (110) extends through the respective slits and is then fixed to different positions.

18. The battery pack according to claim 1, wherein each of the first bus bar (230) and the second bus bar (240) has a smaller number of slits than the unit cells (110), and two or more electrodes are sequentially stacked and fixed at the same point of the bus bar.

19. The battery pack according to claim 1, further comprising a buffer member (300) disposed between the sub-modules (100).

20. A secondary battery comprising the battery pack according to any one of claims 1 to 19.